Whole-house audio with free hardware and software

The topological address (route from USB HCD to the given port on switch) is unique to each device. So even if enumeration order is not stable or if you power devices in different order you can still precisely distinguish which device is connected to which port. And yes, it is probably easiest to do initial setup once by playing sample to single zone. But if you know the cables wiring from device to room and hub port number the device is connected to then there is no need for any device serial number (which we usually have anyway) in descriptors.